I've always found it depends where they come from. The Romans and northerners can be appallingly rude but the ones from the south are nice enough - mind you they can afford to be because if they don't like you they'll just give the order.................
Oddly, the gerries seem to have a reputation as being rude and obnoxious tourists but I've always got on fine with them.
Central london was mobbed with them on Champions league day and they were fine. And if a German tourist asks you something then they're always really polite. Never had an issue with them at all. It could of course be that, aside from being annoyed by 2 narcissistic Italians who can't look at a national land mark without wanting to have their mugs pictured in front of it, I'm actually a very nice person who gets on well with everybody.